1. Field of the Invention
The invention relates to the field of coffee makers and to a method for operating such a coffee maker.
2. Description of the Related Art
Substantially two types of coffee makers can be found on the market. The first includes so-called “semi-automatic machines” or “portafilter machines”, in the case of which the coffee powder is metered from a mill located next to the coffee maker into a portafilter (brewing pan comprising brewing filter and outlet opening), which is then clamped to the coffee maker (see, e.g., publication EP 2 314 188 A1). The brewing chamber is thereby sealed to the top in a pressure-tight manner by means of a distribution filter, which is fixedly installed in the coffee maker. The coffee maker subsequently meters hot water under pressure through this portafilter, which then dispenses the brewed coffee directly into the cup. The coffee quality is controlled substantially by the operator, namely by setting the grinding degree at the provided mill and by means of the force exerted in response to the so-called “tampering” (the compacting of the material to be ground in the portafilter). Under ideal conditions, the brewing result—aroma and crema—is of unbeatable quality. Many consumers associate ideal coffee quality with this design of a coffee maker. However, this design requires trained personnel, who are proficient in setting the grinding degree and the tampering—highly fluctuating coffee qualities are to be expected otherwise. The portafilter machines can be produced in a somewhat cost-efficient manner, because they are of low technical complexity.
The second type of coffee maker includes “fully-automatic machines” that are equipped with plunger brewers and built-in mills (see, e.g., EP 1955 624 A1 or EP 0 605 750 A1 or WO 03/043470). The built-in mill meters the coffee powder into a plunger-cylinder arrangement, which, on principle, consists of a cylinder, an upper and a lower plunger (the plungers, however, in each case encompass filter surfaces, which serve as (lower) brewing or (upper) distribution filter, respectively). The cylinder is subsequently closed by means of the plungers and hot water flows across the filters through the coffee, through a discharge tube across an outlet into the cup. The coffee quality of such machines is not as good as in the case of a semi-automatic machine, even with ideal design and with ideal setting conditions. The main cause for this is that the automatic plunger-cylinder arrangement is sensitive with regard to the very fine grinding degree settings, because, due to the friction ratio, the contact pressure of the plunger cannot be controlled as finely as it is possible manually in the case of the semi-automatic machine. On principle, a line and outlet system, which partially destroys the produced crema again and which cools-down the coffee, follows downstream from the brewing device. However, the coffee quality, which is attained, is very stable due to the fully-automatic production and the control of the process parameters and hardly differs from cup to cup, the quality is not dependent on the operator. Devices of this type are significantly more expensive as compared to semi-automatic machines, because the brewing device is a relatively complex structure.
However, coffee makers that are equipped with portafilters and that encompass a built-in mill, are also available on the market (see, e.g., publication WO 2010/085850 A1). For filling purposes, the portafilter is held therein underneath a separate mill discharge and is inserted into the brewing position as described in the case of the semi-automatic machine.
A generic coffee machine is known from CN 201578093 U.
It is thus an object of the invention to create a coffee maker, which combines the advantages of both designs, namely the simplicity and the high possible coffee quality of the semi-automatic machine and the stability of the result of a fully-automatic machine. If possible, the amount of work for the operator is to also be reduced as compared to that of the semi-automatic machine.
It is furthermore an object of the invention to specify a method for operating such a coffee maker.